CN114504556A

CN114504556A - Preparation method of PLGA drug-loaded microspheres and PLGA drug-loaded microspheres

Info

Publication number: CN114504556A
Application number: CN202210030495.7A
Authority: CN
Inventors: 王佳冕
Original assignee: Shenzhen National Research Institute of High Performance Medical Devices Co Ltd
Current assignee: Shenzhen National Research Institute of High Performance Medical Devices Co Ltd
Priority date: 2022-01-12
Filing date: 2022-01-12
Publication date: 2022-05-17

Abstract

The invention discloses a preparation method of PLGA drug-loaded microspheres and PLGA drug-loaded microspheres prepared by the preparation method of the PLGA drug-loaded microspheres. The preparation method of the PLGA drug-loaded microsphere comprises the following steps: providing a mixed solution of PLGA and a drug-loaded substance; carrying out electrostatic spraying processing on the mixed solution of the PLGA and the loaded medicine to obtain a processed mixture; and separating the needed PLGA medicine carrying microspheres from the processing mixture. The data in the embodiment section of the specification show that the PLGA drug-loaded microspheres prepared by the preparation method of the PLGA drug-loaded microspheres have higher drug-loaded rate, and compared with the traditional PLGA drug-loaded microspheres, the drug-loaded rate of the PLGA drug-loaded microspheres prepared by the preparation method of the PLGA drug-loaded microspheres is improved. In addition, the preparation method of the PLGA drug carrying microsphere can improve the drug carrying efficiency of the PLGA drug carrying microsphere by regulating and controlling receiving solutions with different concentrations and different types.

Description

Preparation method of PLGA drug-loaded microspheres and PLGA drug-loaded microspheres

Technical Field

The invention relates to the technical field of periodontitis treatment, in particular to a preparation method of PLGA drug-loaded microspheres and PLGA drug-loaded microspheres.

Background

Periodontitis is the most prominent cause of tooth loss and is often closely associated with systemic disease. It has been rated as the 11 th global pandemic in 2016. Currently, the main treatment is mechanical removal of pathogenic bacterial membranes. But mechanical removal can produce scratches on the tooth roots. Thus, rapid re-colonization of bacteria after debridement often leads to the recurrence of periodontitis in susceptible patients [1,2 ]. In this case, local release antibiotics are needed for adjuvant treatment, such as injection of antibacterial or anti-inflammatory agents directly into the periodontal pocket [3 ]. At present, no periodontitis slow-release system with long drug release time still exists in China. Therefore, a periodontitis slow-release system with a long-time drug release function can realize the complete cure of periodontitis.

Various types of intra-periodontal pocket drug delivery systems for the treatment of periodontal disease have been developed and long-lasting drug delivery is achieved, including fibers, slow-release sticks, films and injectable gels developed earlier, and newer micro/nanoparticle systems and responsive gel systems, etc. [4,5 ]. Generally, injectable gels provide a much faster and easier way to administer than films, slow-release sticks and fibers [6,7 ]. However, the gel has a limited time for releasing the drug, which greatly increases the number of times of the patient's return visits. The prolonged release time requires a higher gel viscosity, which impairs its flowability and injectability. Compared with a gel system, the polylactic acid-glycolic acid copolymer microparticles (PLGA drug-loaded microspheres) have more remarkable advantages. As a medicine carrier for local release, the PLGA medicine carrying microspheres can realize long-acting medicine release, have higher medicine encapsulation rate, excellent injectability, biocompatibility and high bioavailability [8-9 ]. Furthermore, microparticles are relatively less cytotoxic than nanoparticles. Therefore, PLGA drug loaded microspheres are the primary choice for periodontitis drug release.

The PLGA drug-loaded microspheres have gained great attention because of the long-term drug release, but the drug-loaded capacity of the PLGA drug-loaded microspheres is relatively low, so the demand can not be met.

[1]R.H.R,D.Dhamecha,S.Jagwani,M.Rao,K.Jadhav,S.Shaikh,L.Puzhankara,S.Jalalpure,Local drug delivery systems in the management of periodontitis:A scientific review,J Control Release 307(2019)393-409。

[2]A.George,P.A.Shah,P.S.Shrivastav,Natural biodegradable polymers based nano-formulations for drug delivery:A review,Int J Pharmaceut 561(2019)244-264。

[3]M.H.Chi,M.L.Qi,A.Lan,P.Wang,M.D.Weir,M.A.Melo,X.L.Sun,B.Dong,C.Y.Li,J.L.Wu,L.Wang,H.H.K.Xu,Novel Bioactive and Therapeutic Dental Polymeric Materials to Inhibit Periodontal Pathogens and Biofilms,Int J Mol Sci 20(2)(2019)。

[4]R.G.S.Manjunath,A.Rana,Nanotechnology in Periodontal Management,Journal of Advanced Oral Research 6(1)(2015)1-8。

[5]G.Goyal,T.Garg,G.Rath,A.K.Goyal,Current Nanotechnological Strategies for an Effective Delivery of Drugs in Treatment of Periodontal Disease,Crit Rev Ther Drug 31(2)(2014)89-119。

[6]M.Ghavami-Lahiji,F.Shafiei,F.Najafi,M.Erfan,Drug-loaded polymeric films as a promising tool for the treatment of periodontitis,J Drug Deliv Sci Tec 52(2019)122-129。

[7]M.Szulc,A.Zakrzewska,J.Zborowski,Local drug delivery in periodontitis treatment:A review of contemporary literature,Dental and Medical Problems 55(3)(2018)333-342。

[8]Q.X.Ji,Q.S.Zhao,J.Deng,R.Lü,A novel injectable chlorhexidine thermosensitive hydrogel for periodontal application:preparation,antibacterial activity and toxicity evaluation,Journal of Materials Science:Materials in Medicine 21(8)(2010)2435-2442。

[9]S.Rajendran,K.S.Kumar,S.Ramesh,S.R.Rao,Thermoreversible in situ gel for subgingival delivery of simvastatin for treatment of periodontal disease,International journal of pharmaceutical investigation 7(2)(2017)101-106。

Disclosure of Invention

Based on the above, a preparation method of PLGA drug-loaded microspheres capable of increasing the drug-loaded amount of PLGA drug-loaded microspheres is needed.

In addition, the PLGA drug-loaded microsphere prepared by the preparation method of the PLGA drug-loaded microsphere is also needed to be provided.

A preparation method of PLGA drug-loaded microspheres comprises the following steps:

providing a mixed solution of PLGA and a drug load;

carrying out electrostatic spraying processing on the mixed solution of the PLGA and the loaded medicine to obtain a processed mixture; and

separating the needed PLGA medicine carrying microspheres from the processing mixture.

In one embodiment, the electrostatic spraying of the mixed solution of PLGA and drug-loaded is performed by: and (2) filling the mixed solution of the PLGA and the loaded medicament into an injector provided with an electrospray needle, applying voltage between the electrospray needle and a receiving solution, pushing the injector, and spraying the mixed solution of the PLGA and the loaded medicament into the receiving solution from the electrospray needle.

In one embodiment, the receiving solution is a polyvinyl alcohol solution, a vitamin E solution, a dimethylaminoborane solution, or a poloxamer 407 solution;

the concentration of the polyvinyl alcohol solution is 0.25-4% W/V, the concentration of the vitamin E solution is 0.03-1% W/V, the concentration of the dimethylaminoborane solution is 0.1-1% W/V, and the concentration of the poloxamer 407 solution is 0.1-1% W/V.

In one embodiment, the voltage applied between the electrospray needle and the receiving solution is 15kV to 20kV, the distance between the electrospray needle and the receiving solution is 10cm to 20cm, the diameter of the electrospray needle is 18G to 27G, and the pushing speed of the injector is 1 μ L/min to 50 μ L/min.

In one embodiment, in the mixed solution of PLGA and the loaded drug, the mass ratio of PLGA to the loaded drug is 5: 0.3 to 0.7.

In one embodiment, the mixed solution of PLGA and drug-loaded is prepared by: and uniformly mixing the PLGA solution and the loaded medicament saturated solution to obtain the mixed solution of the PLGA and the loaded medicament, wherein the concentration of the PLGA solution is 0.1 g/mL-0.16 g/mL.

In one embodiment, the solvent of the PLGA solution is acetonitrile or acetone, the solute of the saturated solution of loaded drug is minocycline, minocycline hydrochloride, doxycycline or doxycycline hydrochloride, and the solvent of the saturated solution of loaded drug is methanol or ethanol.

In one embodiment, the PLGA solution is prepared by: dissolving the PLGA in a solvent of the PLGA solution, and continuously stirring until no obvious crystallization occurs, and stopping after half an hour to obtain the PLGA solution;

the drug-loaded saturated solution is prepared by the following operations: and dissolving the loaded drug into the solvent of the loaded drug saturated solution, and dissolving by using a vortex vibration mode to obtain the loaded drug saturated solution.

In one embodiment, the step of separating the desired PLGA drug-loaded microspheres from the process mixture comprises: centrifuging the processed mixture to remove a liquid phase to obtain PLGA drug-loaded microspheres, dispersing the PLGA drug-loaded microspheres into ultrapure water, pre-freezing at-75 ℃ to-80 ℃ for 1h to 12h, and freeze-drying to obtain the dry PLGA drug-loaded microspheres.

PLGA drug-loaded microspheres are prepared by the preparation method of the PLGA drug-loaded microspheres.

The data in the embodiment section of the specification show that the PLGA drug-loaded microspheres prepared by the preparation method of the PLGA drug-loaded microspheres have higher drug-loaded rate, and compared with the traditional PLGA drug-loaded microspheres, the drug-loaded rate of the PLGA drug-loaded microspheres prepared by the preparation method of the PLGA drug-loaded microspheres is improved.

In addition, the preparation method of the PLGA drug carrying microsphere can improve the drug carrying efficiency of the PLGA drug carrying microsphere by regulating and controlling receiving solutions with different concentrations and different types.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Wherein:

fig. 1 is a flowchart of a preparation method of PLGA drug-loaded microspheres according to an embodiment.

Fig. 2 is a drug loading rate test result chart of PLGA drug-loaded microspheres prepared in example 1.

Fig. 3 is a drug loading rate test result chart of PLGA drug-loaded microspheres prepared in example 2.

Fig. 4 is a graph showing the drug loading rate test results of PLGA drug-loaded microspheres prepared in example 3.

Fig. 5 is a drug loading rate test result chart of PLGA drug-loaded microspheres prepared in example 4.

Fig. 6 is a drug loading rate test result chart of PLGA drug-loaded microspheres prepared in example 5.

FIG. 7 is a graph showing the test result of the drug release time of PLGA drug-loaded microspheres prepared in example 1.

FIG. 8 is a graph showing the test result of the drug release time of PLGA drug-loaded microspheres prepared in example 2.

FIG. 9 is a graph showing the test result of the drug release time of PLGA drug-loaded microspheres prepared in example 3.

FIG. 10 is a graph showing the test result of the drug release time of PLGA drug-loaded microspheres prepared in example 4.

FIG. 11 is a graph showing the test result of the drug release time of PLGA drug-loaded microspheres prepared in example 5.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

With reference to fig. 1, the invention discloses a preparation method of frontal PLGA drug-loaded microspheres of an embodiment, comprising the following steps:

s10, providing a mixed solution of PLGA and the loaded medicine.

In this embodiment, a mixed solution of PLGA and a drug-loaded is prepared by: and uniformly mixing the PLGA solution and the loaded medicament saturated solution to obtain a mixed solution of PLGA and the loaded medicament, wherein the concentration of the PLGA solution is 0.1 g/mL-0.16 g/mL.

The concentration of the drug loaded saturated solution is determined by the actual drug loaded and solvent.

In other embodiments, the mixed solution of PLGA and drug-loaded may be prepared by other methods as long as a uniform solution is obtained.

In this embodiment, the PLGA may be acid-terminated or lipid-terminated.

In this embodiment, the solvent of the PLGA solution is acetonitrile or acetone, the solute of the saturated solution loaded with the drug is minocycline, minocycline hydrochloride, doxycycline hydrochloride, or doxycycline hydrochloride, and the solvent of the saturated solution loaded with the drug is methanol or ethanol.

The specific choice of the solvent (or drug-loaded solvent) for the PLGA solution is required to satisfy the requirements of solubility, non-toxicity (or low toxicity) and electrostatic spray processing in S20, i.e., theoretically, a solvent satisfying the above requirements can be used as the solvent (or drug-loaded solvent) for the PLGA solution.

In this embodiment, the PLGA solution is prepared by: and dissolving PLGA in a solvent of the PLGA solution, and continuously stirring until no obvious crystallization occurs, and stopping after half an hour to obtain the PLGA solution.

Generally, the resulting PLGA solution is a transparent viscous liquid.

In this embodiment, the drug-loaded saturated solution is prepared by: and dissolving the loaded drug into the solvent of the loaded drug saturated solution, and dissolving in a vortex vibration mode to obtain the loaded drug saturated solution.

The resulting drug-loaded saturated solution needs to be stored at low temperature of 4 ℃.

In a specific preparation process, the mass ratio of the PLGA to the loaded drug can be set according to actual requirements.

Preferably, in the embodiment, in the mixed solution of PLGA and the loaded drug, the mass ratio of PLGA to the loaded drug is 5: 0.3 to 0.7.

And S20, performing electrostatic spraying processing on the mixed solution of the PLGA and the loaded drug obtained in the step S10 to obtain a processing mixture.

The electrostatic spraying processing is a process of atomizing a polymer solution into balls by using a high-voltage electric field, and microspheres with different shapes can be obtained by adjusting process parameters and the properties of the solution.

In this embodiment, the electrostatic spraying of the mixed solution of PLGA and the loaded drug is performed by: and (3) filling the mixed solution of the PLGA and the loaded medicament into an injector provided with an electrospray needle, applying voltage between the electrospray needle and the receiving solution, pushing the injector, and spraying the mixed solution of the PLGA and the loaded medicament into the receiving solution from the electrospray needle.

It should be noted that the collector needs to be shaken continuously during the receiving process, so as to avoid aggregation of the worthy PLGA drug-loaded microspheres.

Preferably, the receiving solution is a Polyvinyl alcohol (PVA) solution, a vitamin e (vitamin e) solution, a Dimethylaminoborane (DMAB) solution, or a Poloxamer 407(Poloxamer 407) solution.

The receiving solution is water solution of different types of surfactants, so that the microspheres can be well dispersed in the liquid solution, and the drug loss of the microspheres in the preparation process is reduced.

In this embodiment, all of the solvents of the polyvinyl alcohol solution, the vitamin E solution, the dimethylaminoborane solution, and the poloxamer 407 solution are ultrapure water.

Preferably, the concentration of the polyvinyl alcohol solution is 0.25% W/V-4% W/V, the concentration of the vitamin E solution is 0.03% W/V-1% W/V, the concentration of the dimethylaminoborane solution is 0.1% W/V-1% W/V, and the concentration of the poloxamer 407 solution is 0.1% W/V-1% W/V.

Here, W/V is a mass-to-volume ratio, and 1% W/V is 1g/100 mL.

Specifically, the concentration of the polyvinyl alcohol solution may be 0.25% W/V, 0.5% W/V, 1% W/V, 2% W/V, 4% W/V, the concentration of the vitamin E solution may be 0.03% W/V, 0.3% W/V, 1% W/V, the concentration of the dimethylaminoborane solution may be 0.1% W/V, 0.25% W/V, 0.5% W/V, 1% W/V, the concentration of the poloxamer 407 solution may be 0.1% W/V, 0.25% W/V, 0.5% W/V, 1% W/V.

In a specific preparation process, specific parameters of electrostatic spraying processing can be set according to actual requirements.

Preferably, in the present embodiment, the voltage applied between the electrospray needle and the receiving solution is 15kV to 20kV, the distance between the electrospray needle and the receiving solution is 10cm to 20cm, the diameter of the electrospray needle is 18G to 27G, and the pushing speed of the injector is 1 μ L/min to 50 μ L/min.

Specifically, the voltage applied between the electrospray needle and the receiving solution was 18kV, the distance between the electrospray needle and the receiving solution was 17cm, the diameter of the electrospray needle was 21G, and the pushing speed of the injector was 10. mu.L/min.

And S30, separating the processed mixture obtained in the S20 to obtain the needed PLGA drug-loaded microspheres.

Specifically, in the present embodiment, S30 is: centrifuging the processed mixture to remove a liquid phase to obtain PLGA drug-loaded microspheres, dispersing the PLGA drug-loaded microspheres into ultrapure water at-75 ℃ to-90 ℃ (preferably-80 ℃) for pre-freezing for 1h to 12h, and then freezing and drying to obtain the dry PLGA drug-loaded microspheres.

In the operation of centrifugation, the rotation speed is 3000rpm to 10000 rpm.

It is noted that when a polyvinyl alcohol solution is used as the receiving solution, a washing step is added because the viscosity of the polyvinyl alcohol solution is too large.

That is, S30 specifically is: centrifuging the processing mixture to remove a liquid phase to obtain PLGA drug-loaded microspheres, washing the PLGA drug-loaded microspheres for three times by using ultrapure water, centrifuging again to remove the ultrapure water, dispersing the PLGA drug-loaded microspheres into the ultrapure water for preservation for 1-12 h, and freeze-drying to obtain the dried PLGA drug-loaded microspheres.

The data in the specific embodiment section of the specification show that the PLGA drug-loaded microspheres prepared by the preparation method of the PLGA drug-loaded microspheres have higher drug-loading rate, and compared with the traditional PLGA drug-loaded microspheres, the drug-loading rate of the PLGA drug-loaded microspheres prepared by the preparation method of the PLGA drug-loaded microspheres is improved.

In addition, the data in the specific embodiment section of the specification can show that the PLGA drug-loaded microspheres prepared by the preparation method of the PLGA drug-loaded microspheres can continuously release the loaded drug for a long time.

The invention also discloses PLGA drug-loaded microspheres prepared by the preparation method of the PLGA drug-loaded microspheres.

The following are specific examples.

Example 1

(1) 5g of acid-terminated PLGA (Purac) was dissolved in 50mL of acetone solution (Sigma-Aldrich) and stirring was continued until no significant crystallization occurred and was stopped after half an hour, whereupon a clear viscous liquid was observed, giving a colorless and transparent PLGA solution.

(2) 0.5g doxycycline hydrochloride (Sigma-Aldrich) was dissolved in a small amount (in terms of solubility) of methanol solution (Sigma-Aldrich) by vortexing until dissolution, and the resulting doxycycline hydrochloride solution was stored at 4 ℃ at a low temperature.

(3) And mixing the PLGA solution with the doxycycline hydrochloride solution, and quickly stirring to obtain a mixed solution.

(4) Performing electrostatic spray processing on the mixed solution obtained in the step (3) by using electrostatic spray processing equipment and respectively using dimethylamino borane solutions (Sigma-Aldrich) with the concentrations of 0.1% W/V, 0.25% W/V, 0.5% W/V and 1% W/V as receiving solutions, filling the mixed solution into a syringe, and pushing at a constant speed of 10 mu L/min. A voltage of 18kV was applied between the electrospray needle (diameter 21G) and the receiving solution, and the preparation distance was set to 17 cm. The collector needs to shake continuously in the receiving process, so that the PLGA drug-loaded microspheres are prevented from being aggregated into a cluster, and a processing mixture is obtained.

(5) After collection, the PLGA drug-loaded microspheres are dispersed in the processing mixture, after the receiving solution is removed by centrifugation, the PLGA drug-loaded microspheres are dispersed in a small amount of ultrapure water, stored for 6 hours at the temperature of minus 80 ℃, and then freeze-dried for 24 hours to obtain the dried PLGA drug-loaded microspheres.

Example 2

(1) 5g of acid-terminated PLGA was dissolved in 50mL of acetone solution, and stirring was continued until no significant crystallization occurred, and then stopped after half an hour, and a clear viscous liquid was observed to give a colorless and transparent PLGA solution.

(2) Dissolving 0.5g of doxycycline hydrochloride into a trace (calculated by the solubility) methanol solution, and performing vortex vibration to dissolve the doxycycline hydrochloride, wherein the obtained doxycycline hydrochloride solution is stored at a low temperature of 4 ℃.

(4) Performing electrostatic spray processing on the mixed solution obtained in the step (3) by using electrostatic spray processing equipment and respectively taking poloxamer 407 solution (Sigma-Aldrich) with the concentration of 0.1% W/V, 0.25% W/V, 0.5% W/V and 1% W/V as receiving solution, and filling the mixed solution into a syringe and pushing the syringe at a constant speed, wherein the speed is 10 mu L/min. A voltage of 18kV was applied between the electrospray needle (diameter 21G) and the receiving solution, and the preparation distance was set to 17 cm. The collector needs to shake continuously in the receiving process, so that the PLGA drug-loaded microspheres are prevented from aggregating to form a cluster, and a processing mixture is obtained.

Example 3

(4) And (3) performing electrostatic spraying processing on the mixed solution obtained in the step (3) by using electrostatic spraying processing equipment and using vitamin E solutions (Sigma-Aldrich) with the concentrations of 0.03% W/V, 0.3% W/V and 1% W/V as receiving solutions respectively, and filling the mixed solution into a syringe and pushing at a constant speed of 10 mu L/min. A voltage of 18kV was applied between the electrospray needle (diameter 21G) and the receiving solution, and the preparation distance was set to 17 cm. The collector needs to shake continuously in the receiving process, so that the PLGA drug-loaded microspheres are prevented from being aggregated into a cluster, and a processing mixture is obtained.

(5) After collection, the PLGA drug-loaded microspheres are dispersed in a processing mixture, after centrifugation is carried out to remove a receiving solution, the PLGA drug-loaded microspheres are dispersed in a small amount of ultrapure water, the mixture is stored for 6 hours at the temperature of 80 ℃, and then the mixture is frozen and dried for 24 hours to obtain the dry PLGA drug-loaded microspheres.

Example 4

(4) Performing electrostatic spray processing on the mixed solution obtained in the step (3) by using electrostatic spray processing equipment and taking polyvinyl alcohol solutions (Sigma-Aldrich) with the concentrations of 0.25% W/V, 0.5% W/V, 1% W/V, 2% W/V and 4% W/V as receiving solutions respectively, filling the mixed solution into a syringe, and pushing at a constant speed of 10 mu L/min. A voltage of 18kV was applied between the electrospray needle (diameter 21G) and the receiving solution, and the preparation distance was set to 17 cm. The collector needs to shake continuously in the receiving process, so that the PLGA drug-loaded microspheres are prevented from being aggregated into a cluster, and a processing mixture is obtained.

Example 5

(1) 5g of acid end group PLGA is dissolved in 50mL of acetone solution, stirring is continuously carried out until no obvious crystallization occurs, and the stirring is stopped after half hour, and transparent viscous liquid can be observed to obtain colorless and transparent PLGA solution.

(5) After collection, the PLGA drug-loaded microspheres are dispersed in the processing mixture, and after the receiving solution is removed by centrifugation, the PLGA drug-loaded microspheres are obtained. The microspheres collected with the polyvinyl alcohol solution require an additional washing step (elution) due to the excessive viscosity of the polyvinyl alcohol solution. The preparation method comprises the following steps of obtaining PLGA drug-loaded microspheres, washing the PLGA drug-loaded microspheres with ultrapure water for three times, centrifuging to remove the ultrapure water, dispersing the PLGA drug-loaded microspheres in a small amount of ultrapure water, preserving the PLGA drug-loaded microspheres for 6 hours at the temperature of-80 ℃, and freeze-drying for 24 hours to obtain the dried PLGA drug-loaded microspheres.

Example 6 drug loading test of PLGA drug loaded microspheres.

(1) 5.0mg of PLGA drug-loaded microspheres prepared in examples 1 to 5 were dissolved in 1mL of chloroform (Sigma-Aldrich, Seelze, Germany), respectively. After complete dissolution, 5mL of ultrapure water was added, followed by stirring and mixing for thirty minutes, and then standing to obtain a transparent layered solution.

(2) The Dox content of the upper aqueous phase of the layered solution was analyzed by measuring the absorption at 360nm using High Performance Liquid Chromatography (HPLC) (BioTek, Synergy HTX, USA).

The drug loading efficiency of the PLGA drug loaded microspheres was calculated using the following formula: EE (%)/(theoretical amount (mg)) × 100% was obtained as shown in fig. 2 to 6.

With reference to fig. 2 to 6, it can be seen that the PLGA drug-loaded microspheres prepared in embodiments 1 to 5 have a high drug-loading rate, and the drug-loading efficiency of the PLGA drug-loaded microspheres can be improved by adjusting and controlling receiving solutions of different concentrations and different types.

Example 7 drug release time testing of PLGA drug loaded microspheres

5.0mg of each of the PLGA drug-loaded microspheres prepared in examples 1 to 5 was added to a 1.5mL-Eppendorf tube (n ═ 3), and 500. mu.L of phosphate buffered saline (PBS; Gibco, Paisley, UK) was added to each tube.

1.5mL-Eppendorf tubes were incubated at 37 ℃ on a rotating plate at a rotation speed of 90 rpm. At each time point (1h, 4h, 24h, 48h, 72h, 7d, 10d, 14d) tubes were centrifuged at 10,000rpm for 2 minutes, resulting in 400 μ L of supernatant for further analysis, filtered and stored.

Fresh PBS was added to the tube. The microspheres were redispersed by vortexing and then returned to the incubator until the next release time point.

The content of the loaded drug in the supernatant obtained from the corresponding test points was measured, respectively, to obtain fig. 7 to 11.

As can be seen from FIGS. 7 to 11, the PLGA drug-loaded microspheres prepared in examples 1 to 5 can release the loaded drug continuously for a long time.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The preparation method of the PLGA drug-loaded microspheres is characterized by comprising the following steps:

providing a mixed solution of PLGA and a drug load;

2. The preparation method of PLGA drug-loaded microspheres according to claim 1, wherein the electrostatic spraying of the mixed solution of PLGA and the loaded drug is performed by: and (2) filling the mixed solution of the PLGA and the loaded medicament into an injector provided with an electrospray needle, applying voltage between the electrospray needle and a receiving solution, pushing the injector, and spraying the mixed solution of the PLGA and the loaded medicament into the receiving solution from the electrospray needle.

3. The preparation method of PLGA drug-loaded microspheres according to claim 2, wherein the receiving solution is a polyvinyl alcohol solution, a vitamin E solution, a dimethyl borane solution or a poloxamer 407 solution;

4. The preparation method of PLGA drug-loaded microspheres of claim 3, wherein the voltage applied between the electrospray needle and the receiving solution is 15kV to 20kV, the distance between the electrospray needle and the receiving solution is 10cm to 20cm, the diameter of the electrospray needle is 18G to 27G, and the pushing speed of the injector is 1 μ L/min to 50 μ L/min.

5. The preparation method of PLGA drug-loaded microspheres according to any one of claims 1 to 4, wherein the mass ratio of PLGA to drug-loaded in the mixed solution of PLGA and drug-loaded is 5: 0.3 to 0.7.

6. The preparation method of PLGA drug-loaded microspheres according to claim 5, wherein the mixed solution of PLGA and drug-loaded is prepared by: and uniformly mixing the PLGA solution and the loaded medicament saturated solution to obtain the mixed solution of the PLGA and the loaded medicament, wherein the concentration of the PLGA solution is 0.1 g/mL-0.16 g/mL.

7. The preparation method of PLGA drug-loaded microspheres according to claim 6, wherein the solvent of the PLGA solution is acetonitrile or acetone, the solute of the saturated solution of the loaded drug is minocycline, minocycline hydrochloride, doxycycline hydrochloride or doxycycline hydrochloride, and the solvent of the saturated solution of the loaded drug is methanol or ethanol.

8. The preparation method of PLGA drug-loaded microspheres according to claim 7, wherein the PLGA solution is prepared by: dissolving the PLGA in a solvent of the PLGA solution, and continuously stirring until no obvious crystallization occurs, and stopping after half an hour to obtain the PLGA solution;

9. The method for preparing PLGA drug-loaded microspheres according to claim 5, wherein the step of separating the desired PLGA drug-loaded microspheres from the process mixture comprises: centrifuging the processed mixture to remove a liquid phase to obtain PLGA drug-loaded microspheres, dispersing the PLGA drug-loaded microspheres into ultrapure water, pre-freezing at-75 ℃ to-80 ℃ for 1h to 12h, and freeze-drying to obtain the dry PLGA drug-loaded microspheres.

10. A PLGA drug-loaded microsphere, which is characterized in that the PLGA drug-loaded microsphere is prepared by the preparation method of the PLGA drug-loaded microsphere as claimed in any one of claims 1 to 9.